1 4.1Backdooring: You are not allowed to attack any tower on the map without creepsupport.2 4.2You have to enter the base with creeps but they dont have to be in the same line as you. As soon as creeps enters the base, the complete base is allowed to be destroyed.3 As long as there were creeps in base when you entered, you are allowed to keep attacking even if they die. If you leave the base at this moment you need to have new creeps in the next attack.4 4.3If a tower is denyable (below 10% HP) and is not a base tower, backdooring rules do not apply.56 DEFINITIONS:7 Creeps "Enter the base" when they are upslope on their way into the base.8 Creepsupport : The creeps are within 600 Range.

Read carefully these are the bd rules for dota and dota like maps (nwu, nvb, bbb, etc)